HTML-prototyping

Unlike many other designers, I NEVER start any project in Photoshop. In stead, I start working from the browser. This of course is after a series of pen-and-paper prototypes and the occasional wireframe, in which many ideas and research have been put with the end user in mind. As soon as I got something useful, suitable for production, I switch to plain HTML5 and start writing all the markup needed for my prototype. Then comes CSS, and the final design comes out of several iterations of feedback, sent back and forth to my client. The main benefit of designing in the browser is the fact people can start using it straight away. You can run user tests, see if any browsers don't cooperate etc.